docs: def messageReceived(self, message):
          """
          Called on incoming message from ZeroMQ.
  
          Dispatches message to back to the requestor.
  
          :param message: message data
          """
          msgId, msg = message[0], message[2:]
          self._releaseId(msgId)
          d, canceller = self._requests.pop(msgId, (None, None))
  
          if canceller is not None and canceller.active():
              canceller.cancel()
  
          if d is None:
              # reply came for timed out or cancelled request, drop it silently
              return
  
          d.callback(msg)